Guide · 5 steps · ~3 min read
Read the meter overnight.
No-use test: if the meter moves, you have flow — hunt it before tips.
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Step 1
Find the dial or digital total
Locate the meter (curb box, basement, utility closet). Note units and the low-flow / leak indicator if present.
Portland Water Bureau says most residential meters have a leak detection dial, often a red or blue triangle or a blue snowflake. It spins quickly when water is running and may move slowly if water is dripping. Lids can be heavy, so lift them carefully and put them back.
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Step 2
Shut off all use
No ice makers, irrigation, or “someone will just rinse a glass.” EPA WaterSense says to check the meter before and after a two-hour period when no water is being used. If the meter changes at all, you probably have a leak. Seattle Public Utilities puts it the same way: if all the water in the house is off and the meter is still turning, you may have a leak. An overnight window works too, as long as nothing runs automatically.
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Step 3
Watch or re-read
If the leak indicator spins or the total climbs, you have continuous flow. Isolate the house shutoff to separate indoor vs service/irrigation.
Portland's steps for that: close the house's main shutoff valve, open a faucet to confirm no water flows, then look at the meter again. If the leak indicator or hand is still moving, water is flowing between the meter and the house valve, possibly an underground leak. If it stopped, the leak is likely inside, such as toilets, faucets, appliances, or garden hoses.
Full leak checklist -
Step 4
Worked example: turn two readings into gallons per day
These readings are an example, not a real bill. A meter that reads in gallons shows 482,310 at 10:00 p.m. and 482,334 at 6:00 a.m., with no water used in between.
- Flow during the test: 482,334 − 482,310 = 24 gallons in 8 hours.
- Per hour: 24 ÷ 8 = 3 gallons.
- Per day, if the flow is steady: 3 × 24 = 72 gallons.
- Per 30-day month: 72 × 30 = 2,160 gallons, or 2,160 ÷ 748 = about 2.9 CCF.
Any change at all is a leak signal under EPA's test; you do not need to reach a threshold. For scale, EPA says nine percent of homes have leaks that waste 50 gallons or more per day, and this example is above that line.
If your meter reads in cubic feet, multiply by 7.48 to get gallons, because one CCF (100 cubic feet) is 748 gallons per EPA WaterSense. Example: 3.2 cubic feet × 7.48 = about 24 gallons. The daily figure assumes the leak runs at the same rate all day; an intermittent leak can be larger or smaller.
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Step 5
Dye-test toilets next
Add a few drops of food coloring to the tank and do not flush. EPA WaterSense says that if any color shows up in the bowl after 10 minutes, you have a leak. Flush afterward so the tank does not stain.
EPA also suggests checking faucet gaskets and pipe fittings for water on the outside of the pipe, which points to surface leaks.
Silent toilet leak cost
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Related diagnosis guides
Keep one primary page per question. These siblings cover the rest of the high-intent set.
Why is my water bill so high?
National diagnosis: usage vs rates vs sewer vs silent leaks.
Silent toilet leak cost
Dye-test, size the waste, fix the flapper before upgrading.
Leaky faucet drip cost
Drip Meter: drips/min → gallons → $/month bill proof.
Sprinkler / irrigation timer spike
Stuck schedules and broken heads before indoor gadgets.
Sudden high water bill
Bill jumped out of nowhere? Four causes, checked in order.
Compare bills month over month
Units per day — not dollars — when the total lies.
Estimated meter read true-up
Catch-up dump after a low estimated read.
Pool fill sewer credit
Gallons you keep vs sewer you may credit.
How water meter reads work
Set dials, match the bill, catch misreads.
Why water pressure fluctuates
24h timeline: municipal demand vs internal pipe/pump.
Toilet dye test
Drop-timer: Slow seep vs Fast waste gal/day.
How runoff retention changes your stormwater bill
Stormwater/impervious fee — Drainage Delay over 48h.
Did a hose timer leave outdoor water on your bill?
Quiet house, jumping bill — check the outdoor timer.
Pressure reducer (PRV) check
Municipal vs recommended PSI — age the valve, size waste.
Why is my water pressure low?
Whole house vs one fixture — name the cause before you call.
Why is my water billing estimated?
Safe Zone vs Shock Zone — prior actual vs this estimate.
FAQ
How long should a no-use meter test last?
EPA WaterSense says to read the meter before and after a two-hour period when no water is being used. Overnight also works if nothing runs automatically, such as irrigation or an ice maker. Portland Water Bureau suggests waiting several hours if the meter hand is not moving at first.
Does any meter movement mean I have a leak?
EPA says that if the meter changes at all during the no-use period, you probably have a leak. Seattle Public Utilities likewise says that if all water in the house is off and the meter is still turning, you may have a leak. There is no minimum amount to reach.
What does the leak indicator on my meter look like?
Portland Water Bureau says most residential meters have a leak detection dial, often a red or blue triangle or a blue snowflake. It spins rapidly when water is running and may move slowly if water is dripping.
How do I dye-test a toilet?
Put a few drops of food coloring in the toilet tank and do not flush. EPA WaterSense says that if any color shows up in the bowl after 10 minutes, you have a leak. Flush afterward to avoid staining the tank.